If the deformation of EN 10297-1 C45 seamless steel pipe is small during the air drawing process, the inner and outer surface layers will generate additional stress due to external pressure and internal tension.
At this time, due to poor deformation and penetration, the extension tendency of the outer surface layer is greater than that of the inner layer. Therefore, additional compressive stress is generated in the outer surface layer of EN 10297-1 C45 seamless steel pipe, and additional tensile stress is generated in the inner surface layer of EN 10297-1 C45 seamless steel pipe.
If the additional tensile stress of the inner surface layer is large, the basic stress and the additional stress during drawing will exceed the degree permitted by the strength of the EN 10297-1 C45 seamless steel pipe, causing transverse cracks on the inner surface.
Under the corresponding mechanical conditions, the EN 10297-1 C45 seamless steel pipe specification increases the chance of internal transverse cracks. Therefore, in the production of EN 10297-1 C45 seamless steel pipe, annealing quality and elimination of hydrogen embrittlement are very important.